PIP install /Cannot fetch index base URL

关于pip install （模块）报错

以安装web2模块为例:

Cannot fetch index base *

Could not find any downloads that satisfy the requirement*

root@server:~# pip install web2py

Downloading/unpacking web2py

 Cannot fetch index base URL http://pypi.python.org/simple/

 Could not find any downloads that satisfy the requirement web2py

No distributions at all found for web2py

Storing complete log in /root/.pip/pip.log

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解决方法 -i http://pypi.douban.com/simple/

pip install web2py -i http://pypi.douban.com/simple/